/Engine/Plugins/Editor/ObjectMixer/ObjectMixer/Source/ObjectMixer/Public/Views/List/ObjectMixerEditorList.h
Force returns result from Filter->ForceGetObjectClassesToFilter. Generally, you want to get this from the public performance cache.
[TSet](API\Runtime\Core\Containers\TSet)< [UClass](API\Runtime\CoreUObject\UObject\UClass) * > ForceGetObjectClassesToFilter()